More and more people are opting for duplex and dual occupancy homes in recent times, and it makes sense. For one, it allows you to live close to aging parents or extended family. Secondly, it gives investors more bang for their buck.
A good duplex design gives both households real privacy, separate entries and their own outdoor space, while still working with your block’s size and orientation.
Quick summary
- A duplex is two attached homes on one block, each with its own entry, kitchen and outdoor space, so both households live independently under one roofline.
- The layouts that work best keep bedrooms away from the shared wall, split parking and services clearly, and give each side its own private outdoor area.
- Building a duplex in Victoria needs council approval and meets extra fire separation rules for the shared wall, making it a popular option for a knock down rebuild.
Why build a duplex?
A duplex (also known as a semi-detached home or, broadly, a dual occupancy home) is two attached dwellings built on the one block of land. Both households live independently under one roofline, separated by a wall.
For families, it’s a chance to have parents close by without living within the same four walls. A duplex lets Grandma and Grandad have their own front door, their own lounge room and their own routine, while still being a short walk from the grandkids. It works in reverse too, with adult kids saving for their first place while staying part of the family home.
For investors, two dwellings on one block means two rents from one piece of land. It’s a straightforward way to improve your return, especially on blocks where land values have climbed faster than what a single home can generate in rent.
Mirrored or individual layout
A mirrored floor plan, where both sides are a flipped copy of each other, is usually the more cost-effective option since the same design and materials are used twice over. It works well on a regular, rectangular block where both dwellings have equal access to light and outlook.
An individual layout gives each side its own design, which costs more to plan and build but makes better use of an irregular block, a sloped site, or a block where one side gets better views or sun than the other.
This is one of the first things to decide, since it shapes everything in the design that follows. Most opt for the simpler option of the mirrored layout.
Orientation and natural light
With two dwellings on one block, it’s easy for one side to end up with all the good light and the other stuck facing south, especially on a side-by-side layout where the block itself doesn’t run north-south.
The best-case scenario is a north-facing block, where both dwellings can then orient their living and outdoor to the north without blocking each other.
A mirrored plan on an east-west running site can leave one household with all the good sun and the other stuck with a gloomier afternoon, even though the two floor plans are identical.
Individual layouts give you more room to move. Instead of balancing the two sides out, you can design each dwelling around natural light. It means you can put the main living area and outdoor space wherever they get the best light, even if the two floor plans end up looking quite different from each other.
Privacy between the two homes
Bedrooms backing onto your neighbour’s living room, or windows looking straight into the other dwelling’s dining room, are the kinds of things that can make dual living situations feel a little too cozy.
Good design keeps areas where you want peace and quiet, like bedrooms and living rooms, away from the shared wall. Bathrooms, entryways, hallways, staircases, and walk-in robes are better placed alongside each other because they’re only used intermittently, rather than for long durations throughout the day.
Talk to your builder about the wall itself too. The National Construction Code already requires a fire rated wall between the two dwellings, and a good acoustic build up goes a long way to stopping noise from carrying through.
Shared or split outdoor space
This depends on the dynamics between the two households.
Some blocks work well with one larger shared yard. It means backyard BBQ dinners with the whole family, and the kids can play with their grandparents without having to hop a fence. For a little more separation, you could opt for a low, gated fence.
If one or both sides are tenanted, or the two households just want their own space, then consider more secluded options. A taller fence, or even two private yards on opposite sides of the building, will give a bit more privacy.
Parking, access and services
Councils require clear vehicle access to each dwelling, so driveway width and turning space should be worked out early.
Also, think about if each dwelling should have its own power, water and gas connections, or if services will be shared. Separate metering costs more upfront but makes life easier down the track if you rent or sell one side.
Knock-down rebuild: turn one home into two
A knock-down rebuild is one of the best ways into a duplex, especially if you’ve got your heart set on a particular block. Instead of chasing the rare vacant block already zoned for two dwellings, you demolish an ageing house and build a duplex in its place.
You’ll need to confirm that the block meets your local council’s minimum size and frontage rules for two dwellings. Plan for services like stormwater and sewer connections for two households instead of one.
Done well, a knock down rebuild duplex project can turn a single ageing home into two modern dwellings that suit today’s buyers and renters far better than the original ever did.
FAQs
Is a duplex the same as a dual occupancy?
Not quite. Dual occupancy is the formal planning term used in Victoria for two dwellings on one lot, attached or detached, sitting on a single title until subdivided. A duplex is specifically the attached version, two homes sharing a common wall, usually built with separate titles in mind.
Do I need a permit to build a duplex?
Most duplex builds need a planning permit as well as a building permit, since council needs to assess things like site coverage, car parking and impact on neighbouring properties.
Can I subdivide a duplex and sell one side?
Often yes, depending on your zoning and title arrangement. Subdivision usually happens after construction, once each dwelling meets the requirements for a separate title. Discuss your subdivision plans with your builder and a planning professional before you start designing.
Is building a duplex a good investment?
It can be, since two dwellings on one block can generate two rental incomes from a single piece of land. As with any investment, it comes down to your specific block, budget and the local rental market.
How Enso Homes can help
We build across Geelong, the Bellarine, the Surf Coast and Golden Plains, and duplex builds are a project type we get asked about more each year.
If you’re planning for a family, or looking at the numbers as an investment, we’ll help you work out what your block can support, then design a layout that gives both households the privacy and space they need.
Get in touch with Enso Homes and we’ll walk you through your options.
